Area Forecast Discussion
Issued by NWS Quad Cities, IA IL
Issued by NWS Quad Cities, IA IL
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225 FXUS63 KDVN 182333 AFDDVN Area Forecast Discussion National Weather Service Quad Cities IA IL 633 PM CDT Tue Jun 18 2024 .KEY MESSAGES... - Heat Advisory continues across the entire area through 8 pm this evening. - Temporary bit of relief from the higher heat levels will come for some in the form of a cold front that will sink southeastward across portions of the area late tonight and Wednesday - There is a Marginal Risk (Level 1 of 5) of severe weather for Wednesday across much of the DVN CWA. - The pattern will remain rather active from Wednesday and through the upcoming weekend, with periodic chances of thunderstorms. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 249 PM CDT Tue Jun 18 2024 Tonight...With Heat Index readings in the mid to upper 90s ongoing, will keep the heat headlines going although it is marginal. The precursor isolated showers and storms now acrs central IA should continue to fade as they try to push to the western fringe of the CWA or continue to move northwest of the local area. Then eyes turn to the MO RVR Valley or the central MN into the south central NE area late this afternoon as many MCS spawning parameters come together acrs these areas. Interesting fine line of convection along the main front inn this favored region ATTM, while an EML is in charge to the east acrs the local area. Right entrance region of upper jet and digging short wave aloft will help be the synoptic scale convection igniter upstream acrs the severe risk area, with resultant linear MCS sweeping into the CWA from the west overnight. The northeast portion of this feature should be making it into northwestern CWA by around 10-11 PM. There may be some outflow gusts ahead of this line reaching 40 KTs or so, but overall with ongoing EML/CAP and less favorable mid level lapse rates feel the line will be coming acrs in a weakening fashion late tonight into Wed morning. Areas east of the MS RVR may not see much rain at all, while some areas/swaths in the northwest may get up to a half inch by Wed morning. Brisk south winds and DPTs to keep low temps up in the low to mid 70s acrs much of the area, although rain-cooled outflow may knock more down into the upper 60s especially west. Wednesday... A few storms or showers may be ongoing/lingering out of Tue night, but coverage and any intensity should continue to fade in the morning. Then with the main incoming cool front or outflow boundaries sagging acrs the CWA or laying out, they will act as a focus for renewed storm development during the afternoon. Still some uncertainty where these boundaries will lay out, as well as extent of heating that we will get or rate of convective debris decay, but at least moderate chance POPs warranted acrs much of the fcst area during the afternoon and early evening. MUCAPEs may range up to 2000 J/kg, but storm layer shear profiles of 20-30 KTs and mid level lapse rates under 6 C/km make for a limited severe storm threat. BUt agree with SPC`s thinking there could be isolated wind gusts of 50-60 MPH or damaging rain loaded down bursts. Warm and moist profiles should limit the max hail size to under severe limits. PWAT`s of 1.6 to 1.8 inches will support locally heavy rain swaths of over an inch. This while other areas receive only a trace. High temps a challenge with all the boundary and cloud debris questions, but will range them from highs only in the mid 70s in the far northwest, to the low 90s in the east/southeast. Heat index`s in theses 90 degree areas may range in the mid to upper 90s, but not worthy of heat headlines with less true heat coverage and cloud cover uncertainties. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Issued at 249 PM CDT Tue Jun 18 2024 Thursday...A day where we may have a few lingering thunderstorms out of Wed night in the north, and then remnant outflow boundaries or the quasi-stationary front itself may act as a focus for renewed shower and storm development Thu afternoon and evening. Despite decent looking CAPE profiles, weak shear and marginal mid level lapse rates will hopefully limit any severe potential except maybe a rain loaded isolated downburst again. Where these afternoon storms may fire still uncertain, but ensemble placement is generally along and north of the I-80 corridor with mid to upper ridging bulging acrs the southeastern DVN CWA off the OH RVR/TN Valley high pressure complex. These storms should fade diurnally as the evening progresses and the upper ridge adjusts northward up the Upper MS RVR Valley into Friday morning. Highs on THu will range from the low to mid 80s north, to the lower 90s in the south. Friday...Amplifying thermal ridge overhead will look to shunt the storm track to the north as the day and night progresses, leaving the local area in hot breezy conditions. But sfc DPTs are currently progged to stay mixed out in the mid 60s, thus the lower humidity may not warrant a heat advisory this day. BUt a better chance for ambient temps to reach the mid 90s in some locations. Saturday through Monday...A hot and more humid airmass with a ridge flattening short wave digging acrs the region may spark strong, heavy rain producing storms late Saturday or Sat night. Associated cool front will also sweep through the area late, which could make for a not as hot and less humid Sunday. Longer term ensembles suggest a flattened steering flow/near zonal acrs the upper CONUS early to mid next week, possibly placing the local area in or near the thermal battle zone and thus MCS track. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 617 PM CDT Tue Jun 18 2024 A VFR, but warm evening will persist tonight through midnight, before a slow moving line of storms approaches eastern Iowa early Wednesday morning. These are expected to be dissipating as they move into eastern Iowa. With timing pushed a bit farther back compared with earlier issuances, but we`re maintaining a rather long duration of Prob30, given the large, but dissipating mode of the storms moving into eastern/northeastern Iowa between 06-12Z. There is likely to be MVFR in patches during the mid morning hours behind this dissipating activity, followed by generally VFR weather in the afternoon, but late in the period, another round of developing storms is expected, closer to the MLI and the Interstate 80 corridor. These storms could bring lowered visibility in heavy rain and gusty winds into the early evening hours Wednesday. && .CLIMATE... Issued at 249 PM CDT Tue Jun 18 2024 Record Warm Minimum Temperatures: June 19: KDBQ: 76/1931 KMLI: 78/1953 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Heat Advisory until 8 PM CDT this evening for IAZ040>042- 051>054-063>068-076>078-087>089-098-099. IL...Heat Advisory until 8 PM CDT this evening for ILZ001-002-007- 009-015>018-024>026-034-035. MO...Heat Advisory until 8 PM CDT this evening for MOZ009-010. && $$ SHORT TERM...12 LONG TERM...12 AVIATION...12 CLIMATE...12